1. Field of Invention
The present invention relates to an ink composition for ink jet recording, which exhibits excellent printing quality on various recording media, can develop a high level of color developing properties particularly on plain papers, and, at the same time, can exhibit high gloss on gloss paper and is excellent in ink reliability such as ejection stability, storage stability, and recovery from clogging, a recording method using this ink composition, and a recorded matter.
2. Background Art
Ink jet recording is a method wherein ink is ejected as droplets through fine nozzle heads to record letters or FIGURES onto the surface of recording media such as paper. Ink jet recording methods which have been put to practical use include a method wherein an electric signal is converted to a mechanical signal using an electrostrictive element to intermittently eject droplets of ink reservoired in a nozzle head section, thereby recording letters or symbols on the surface of a recording medium, and a method wherein an ink liquid, reservoired in a nozzle head section, in its portion very close to the ejection portion is rapidly heated to create a bubble and droplets of the ink are intermittently ejected by volume expansion created by the bubble to record letters or symbols on the surface of a recording medium.
In recent years, there is an increasing tendency toward the use of printed matter, formed by printing with an ink jet printer, as a display in an indoor environment as well as in an outdoor environment for advertisement or appreciation purposes, and the development of an ink having excellent fastness properties such as excellent lightfastness, gasfastness, and waterfastness has been demanded. To meet this demand, an ink using a pigment having excellent fastness properties such as excellent lightfastness, waterfastness, and gasfastness as a colorant has been developed.
JP H11 (1999)-209672 proposes a water-based pigment ink comprising a pigment covered with a specific polymer, which water-based pigment ink has a high level of color developing properties and excellent lightfastness. JP H10 (1998)-120956 proposes an ink set comprising a combination of specific pigments. Further, JP H10 (1998)-219166 and JP H11 (1999)-49998 propose an ink composition using a quinacridone pigment or a magenta solid solution pigment as a pigment for use for a magenta color, which ink composition has color rendering properties comparable with magenta dyes and, at the same time, is excellent in lightfastness and gasfastness.
Further, a water-based ink containing a surfactant and a polymeric dispersant added thereto and having excellent pigment dispersion, and an ink comprising a pigment as a colorant covered with a dispersing resin have been proposed. Inks with fine particles of pigment having a given particle diameter dispersed therein exhibit excellent color developing properties on various recording media, particularly on plain papers.
When the ink with fine particles of pigment dispersed therein is printed on recording media having a smoothly processed surface such as gloss paper, however, glossiness of the recorded part is sometimes deteriorated by irregular reflection of light.
Further, in the water-based ink with a surfactant and a polymeric dispersant added thereto, upon the vaporization of water and other volatile components in the course of drying of the ink after deposition of the ink onto the recording medium, the dispersion stable system of the ink is broken, often disadvantageously leading to the aggregation of the pigment. As a result, the aggregate of this pigment deteriorates the gloss of the recorded part, renders the gloss of the printed image uneven, and sometimes results in deteriorated printing quality.